turbo spools stupid fast - transition knock

vacuum 6

I have chuckers
Update: installed check valve and lowered turn on to ~2 psi. Only seeing 1d of knock on initial hit. Engine seems to bog a little but I’ll tune that out. The check valve is a nice option to Julio’s kit.
 

DMan

buh bye
This is an interesting and timely thread Vacuum6.

I have the check valve installed, and dual 20 nozzles. I am getting transitional, audible (not false) knock only during spool up, about 6-7 degrees then it goes away.

I have my gain at 4.8 ish. Turn on at 9:30 (about 5psi) and initial around 1:30. I'm thinking I should turn on even sooner to get things moving earlier. Any reactions to the above?
 

Chuck Leeper

Toxic old bastard
Staff member
I have the check valve installed, and dual 20 nozzles. I am getting transitional, audible (not false) knock only during spool up, about 6-7 degrees then it goes away.
What kind of power are you making?
From the conversations I've had w/ Julio, a single nozzle should handle up to 900 FW.
Unless you are way above that, I wonder if the knock is over fueling.. AKA "rich knock".
 

Pronto

Chaos is a ladder.
Hi Denis, Al told me you were working on your GN again. Do you have a Powerlogger? You can see how fast the spool is and how the a/f is doing with a log.
 

DMan

buh bye
What kind of power are you making?
From the conversations I've had w/ Julio, a single nozzle should handle up to 900 FW.
Unless you are way above that, I wonder if the knock is over fueling.. AKA "rich knock".
Hi Denis, Al told me you were working on your GN again. Do you have a Powerlogger? You can see how fast the spool is and how the a/f is doing with a log.
Thanks Gents

Chuck - I think I’m in the 450-500 range on power. I can see my AFRs and I don’t think I was going too rich.

Pronto I do have a powerlogger but I’ve been going mostly by Scanmaster readings, my wideband and EGTs.

since my last post I figured I needed to get things flowing sooner to stay ahead of the detonation. I adjusted my turn on to be even sooner - it’s around 1 psi now. I left initial the same at 1:30. I turned gain up to 6. Transitional audible detonation is gone, but I know I’m flowing too much now as EGTs are on the low side. I have some headroom with spark timing so I might bring that up a notch and see how the car responds. Regardless I think I can dial the initial back - I only want a dribble at 1 psi - enough that the pump and lines are primed.
 

vacuum 6

I have chuckers
What kind of power are you making?
From the conversations I've had w/ Julio, a single nozzle should handle up to 900 FW.
Unless you are way above that, I wonder if the knock is over fueling.. AKA "rich knock".
Agree with this. I'm making 500 WHP. Everything is set back to factory settings with gain knob at 6.

I'm running 25# with 24/22°.
 
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